Cathode active materials for secondary batteries
A cathode active material of formula LiNi x Mn y Al z M α O 2-ε B ε or NaNi x′ Mn y′ Al z′ M′ α′ O 2-ε′ B ε′ , wherein M is a combination of Ti, and Mg; M′ is Ti, Mg, or a combination of thereof; B is selected from the group of F, S, Se, or Cl; 0.8<x<1, 0<y<0.2, 0<z≤0.2, 0≤α≤0.2, 0≤ε≤0.1, 0.5<x′<1, 0<y′<0.5, 0<z′≤0.2, 0≤α′≤0.2, and 0≤ε′≤0.1. The particle is a single crystal, a single particle, or a secondary particle comprising a plurality of primary particles; and the particle is a uniform composition or a concentration gradient composition.
1. A cathode active material of formula LiNi x Mn y Al z M α O 2-ε B ε or NaNi x′ Mn y′ Al z M′ α′ O 2-ε′ B ε′ ;
wherein:
M is a combination of Ti and Mg;
M′ is Ti, Mg, or a combination thereof;
B is F, S, Se, or Cl; and
0<z≤0.2, 0.8<x<1, 0<y<0.2, 0≤α≤0.2, and 0<ε≤0.1
0<z′≤0.2, 0.5<x′<1, 0<y′<0.5, 0≤α′≤0.2, and 0<ε≤0.1; and
the active material is a single crystal.
2. The cathode active material of claim 1 having the formula LiNi x Mn y Al z Ti j Mg k O 2-ε B ε , wherein 0<z≤0.1, 0<j≤0.05, and 0<k≤0.05, and the sum of z, j, and k is ≤0.1.
3. The cathode active material of claim 1 having the formula NaNi x′ Mn y′ Al z′ M′ α′ O 2-ε′ B ε′ , wherein M′ is Ti, Mg, or a combination thereof; and wherein the sum of z′ and α′ is <0.2.
4. A process of preparing the cathode active material of claim 1 , the process comprising:
providing start aqueous solution of Ni, Mn, Al, and M or M′ salts;
combining the aqueous solutions with a chelating agent and a precipitating agent to form a precipitate;
mixing the precipitate with a lithium or sodium salt to form a mixture; and
heating-treating the mixture to form the cathode active material;
wherein M is a mixture of Ti, and Mg, and M′ is Ti, Mg, or a combination thereof.
5. The process of claim 4 , wherein at least two start solutions include varying the concentrations of the salt of Ni, Mn, Al, and M or M′ such that a concentration gradient of the Ni, Mn, Al, and/or M or M′ is established in particles of the precipitate along a vector radius defined from a center of the particle to a surface.
6. The process of claim 5 , wherein:
the heat-treating comprises at least one calcination step at a heating rate to a temperature of about 680° C. to about 1200° C.
the calcination step is conducted in an oxygen atmosphere, an air atmosphere, or in an oxygen-enriched air atmosphere.
7. A particle of cathode active material of formula LiNi x Mn y Al z M α O 2-ε B ε or NaNi x′ Mn y′ Al z′ M′ α′ O 2-ε′ B ε′ ;
wherein:
M is a combination of Ti and Mg;
M′ is Ti, Mg, or a combination thereof;
B is F, S, Se, or Cl;
0<z≤0.2, 0.5<x<1, 0<y<0.5, 0≤α≤0.2, and 0<ε≤0.1
0<z′≤0.2, 0.5<x′<1, 0<y′<0.5, 0≤α′≤0.2, and 0<ε′≤0.1;
the particle is a single crystal.
8. The particle of cathode active material of claim 7 having the formula LiNi x Mn y Al z Ti j Mg k O 2-ε B ε , wherein 0<z≤0.1, 0<j≤0.05, 0<k≤0.05, and wherein the sum of z, j, and k is ≤0.2.
9. The particle of cathode active material of claim 7 having the formula NaNi x′ Mn y′ Al z′ M′ α′ O 2-ε′ B ε′ , wherein M′ is Ti, Mg, or a combination thereof and wherein the sum of z and α′ is ≤0.1.
10. The particle of cathode active material of claim 7 , wherein the particle is generally spherical and has a diameter of about 10 nm to about 10 μm.
11. The particle of claim 7 further comprising a dopant cation.
12. The particle of claim 11 , wherein the dopant cation includes an alkaline earth metal element or a transition metal element other than Ni, Co, Mn, and Al or combinations of any two or more thereof.
13. The particle of claim 7 further comprising a surface coating.
14. The particle of claim 13 , wherein the surface coating comprises a metal oxide, a metal fluoride, a metal phosphate, a conductive carbon coating, or a combination of any two or more thereof.